1. Guangxi Key Laboratory of Nonferrous Metals and Special Materials Processing, College of Materials Science and Engineering, Guilin University of Technology, Guilin 541004, China
2. Baotou Research Institute of Rare Earths, Baotou 014060, China
3. Key Laboratory of New Processing Technology for Nonferrous Metal & Materials, Ministry of Education/Guangxi Key Laboratory of Optical and Electronic Materials and Devices, Guilin University of Technology, Guilin 541004, China